1. Field of the Invention
The present invention relates to an extrusion apparatus, more particularly to an apparatus of the rotor and barrel type for the reduction in size of vulcanized rubber in the form of pepper corn size pieces.
2. Description of the Prior Art
One present day method for producing pepper size pieces of vulcanized rubber from scrap tires can be considered technically successful. To reduce this material into small powder size pieces the material is frozen by means of liquid nitrogen and crushed in a ball mill. The objection to this process is the cost which limits the use of the reclaimed rubber in all but a few salable items. In any event, the growing size of scrap tire piles indicates that the cost of reclaiming must be reduced.
U.S. Pat. No. 3,375,549 discloses the barrier type extruder that is used world wide, particularly in plastic film extrusion. This patent provides a square edged entrance to the restrictive clearance barrier top to barrel bore, for the leading off of the fine and fluent process material, but this patent does not teach the use of that extruder for reducing rubber from scrap tires.